Differential impacts of trail and ultra-trail running on cytokine profiles: An observational study.

BACKGROUND Endurance running events are known to cause inflammation and result in increased cytokine production. However, the effects of ultramarathons on cytokine profiles are not well characterized. OBJECTIVE The aim of this study was to describe and compare the effects of a trail (40 km) race and an ultra-trail (171 km) race on leukocyte concentrations and cytokine profiles. METHODS The study was conducted during the Ultra-Trail du Mont Blanc® ultra-marathon running event, and included 11 runners who completed the 40 km trail run and 12 runners who completed the 171 km ultra-trail. Blood samples were taken before and after the races. RESULTS Leukocyte concentrations significantly increased after both races. Circulating levels of IL-6, IL-1β, MCP-1, and IFN-γ were significantly higher after the longer race compared to the shorter race. Furthermore, while both races resulted in significant increases in IL-6 and IL-8, only the longer race resulted in significant increases in MIP-1β, IL-7, IL-17a, and IL-4. CONCLUSIONS These results illustrate that a 171 km ultra-trail race results in greater modulations in cytokine profiles than a traditional trail race.